Genetic studies suggest that many of our evolutionary trees may be very wrong

Genetic studies suggest that many of our evolutionary trees may be very wrong

Reconstruction of the phylogenetic tree of Rodentia (rodent) on the basis of their entire genome. Image via Wiki Commons.

Ever since Darwin published and popularized the idea of ‚Äč‚Äčevolution, researchers have begun building evolutionary trees – also called phylogenetic trees – branch diagrams that show the evolutionary relationships between different species that share different characteristics.

It is a very useful and simple tool, except that it can be quite wrong, say the authors of a new study.

Genes do not lie

If you were a biologist in the 19th or 20th century and wanted to classify animals, your options were limited. You could study the ecosystem and the role of the animal in it, detail the morphological properties of the species, but that was quite a lot – you had to rely a lot on what things looked like other things.

But in recent years, the advent of genetic analysis has opened new doors for classifying species. As rapid genome sequencing became relatively inexpensive and readily available, researchers had new tools to see which species were related to which, and they began to notice that things were sometimes not as expected.

Sometimes a species can turn out to be so several species, or species that are thought to be closely related can actually be quite different. Matthew Wills, professor of evolutionary paleobiology at the Milner Center for Evolution at the University of Bath, says that “it turns out that we have many of our evolutionary trees wrong.

“For over a hundred years, we have classified organisms according to their appearance and are anatomically complex, but molecular data often tell a completely different story.”

The problem is that rather unrelated beings often evolve in somewhat similar ways. For example, if you are just watching flying, you may be tempted to think that bats and birds are closely related – when it could not be further from the truth. Of course, any biologist can say that bats and birds are very different, but sometimes the differences are more subtle and can be difficult to say. For example, many insects show similar mouth parts, even though they do not have them be close relatives. This is called convergent evolution: the independent development of similar characteristics in different groups of animals.

Molecular data show that elephant mussels are more closely related to elephants than to beaked mice. Image credits: Danny Ye.

In the new study, Wills and colleagues compared 48 pairs of morphological and molecular data, and found that convergent evolution is more common than previously thought, and as a result, several “traditional” evolutionary trees are not as accurate as previously thought.

“Our study statistically proves that if you build an evolutionary tree of animals based on their molecular data, it often fits much better with their geographic distribution,” Wills said in a press release. “Where things live – their biogeography – is an important source of evolutionary evidence known to Darwin and his contemporaries.”

“For example, small elephant snails, earthworms, elephants, golden moles and swimming lizards have all come from the same large branch of mammalian evolution – even though they look completely different from each other (and live in very different ways). Molecular trees have put them all together in a group called Afrotheria, so-called because they all come from the African continent, so the group matches the biogeography. “

In addition to helping biologists better understand these biological relationships, this study also shows that we should not rely on things that seem similar. In addition, it shows that evolution does not always create new things – instead, it seems to tend to produce something similar over and over again. Jack Oyston, research assistant and first author of the article, concludes:

“The idea that biogeography can reflect evolutionary history was a big part of what led Darwin to develop his theory of evolution through natural selection, so it is quite surprising that it was not directly considered as a way to test the accuracy of evolutionary trees. the way before now. “

“What is most exciting is that we find strong statistical evidence that molecular trees fit better not only in groups like Afrotheria, but also over the trees of life in birds, reptiles, insects and plants.”

“It’s such a widespread pattern makes it much more potentially useful as a general test of various evolutionary trees, but it also shows how far-reaching convergent evolution has been in deceiving us.”

The study was published in Communication Biology.

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